The overall objective of the proposed research is the specification and understanding of the development in children and adults of spatial representations of large environments (distal arrangements of landmarks). The research is conceptualized within a comparative-developmental framework proposed by Siegel and White (1975). Within this framework learning (i.e., qualitative and quantitative changes in behavior over diverse temporal spans) is construed as a developmental process. The proposed research focuses on the nature and development of visual-spatial knowledge of environmental landmarks and the construction of spatial representations from this knowledge. Within a recognition-in-context-memory paradigm, Ss will be shown objects (slides, pictures, or in films) and asked to identify from an array both the object itself, and the context in which it had been presented originally. Studies are designed to specify the features and boundary conditions (affective, spaal, and temporal) of landmarks which get registered in memory and how these change with development. Within a reconstruction of spatial layouts paradigm, Ss will be given a series of encounters (varying in exposure time and/or the nature of the encounter) with a spatial layout of landmarks and routes. Following each encounter Ss will be instructed to build a replica of the layout (given a blank layout and identical elements). Ss' performance will be videotaped so that a real-time analysis of their "construction" can be done. Studies are designed to specify the developmental course of how the landmarks become integrated into configurations. Both the development of landmark recognition and of layout construction in children and that in adults over shorter periods of time (e.g., over increasing exposure intervals and encounters) will be studied concomitantly.